1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

//! Lists have various ways of being animated, this module implements them.
//!
//! See https://drafts.csswg.org/web-animations-1/#animating-properties

/// https://drafts.csswg.org/web-animations-1/#by-computed-value
pub mod by_computed_value {
    use crate::values::{
        animated::{Animate, Procedure},
        distance::{ComputeSquaredDistance, SquaredDistance},
    };
    use std::iter::FromIterator;

    #[allow(missing_docs)]
    pub fn animate<T, C>(left: &[T], right: &[T], procedure: Procedure) -> Result<C, ()>
    where
        T: Animate,
        C: FromIterator<T>,
    {
        if left.len() != right.len() {
            return Err(());
        }
        left.iter()
            .zip(right.iter())
            .map(|(left, right)| left.animate(right, procedure))
            .collect()
    }

    #[allow(missing_docs)]
    pub fn squared_distance<T>(left: &[T], right: &[T]) -> Result<SquaredDistance, ()>
    where
        T: ComputeSquaredDistance,
    {
        if left.len() != right.len() {
            return Err(());
        }
        left.iter()
            .zip(right.iter())
            .map(|(left, right)| left.compute_squared_distance(right))
            .sum()
    }
}

/// This is the animation used for some of the types like shadows and filters, where the
/// interpolation happens with the zero value if one of the sides is not present.
///
/// https://drafts.csswg.org/web-animations-1/#animating-shadow-lists
pub mod with_zero {
    use crate::values::animated::ToAnimatedZero;
    use crate::values::{
        animated::{Animate, Procedure},
        distance::{ComputeSquaredDistance, SquaredDistance},
    };
    use itertools::{EitherOrBoth, Itertools};
    use std::iter::FromIterator;

    #[allow(missing_docs)]
    pub fn animate<T, C>(left: &[T], right: &[T], procedure: Procedure) -> Result<C, ()>
    where
        T: Animate + Clone + ToAnimatedZero,
        C: FromIterator<T>,
    {
        if procedure == Procedure::Add {
            return Ok(left.iter().chain(right.iter()).cloned().collect());
        }
        left.iter()
            .zip_longest(right.iter())
            .map(|it| match it {
                EitherOrBoth::Both(left, right) => left.animate(right, procedure),
                EitherOrBoth::Left(left) => left.animate(&left.to_animated_zero()?, procedure),
                EitherOrBoth::Right(right) => right.to_animated_zero()?.animate(right, procedure),
            })
            .collect()
    }

    #[allow(missing_docs)]
    pub fn squared_distance<T>(left: &[T], right: &[T]) -> Result<SquaredDistance, ()>
    where
        T: ToAnimatedZero + ComputeSquaredDistance,
    {
        left.iter()
            .zip_longest(right.iter())
            .map(|it| match it {
                EitherOrBoth::Both(left, right) => left.compute_squared_distance(right),
                EitherOrBoth::Left(item) | EitherOrBoth::Right(item) => {
                    item.to_animated_zero()?.compute_squared_distance(item)
                },
            })
            .sum()
    }
}

/// https://drafts.csswg.org/web-animations-1/#repeatable-list
pub mod repeatable_list {
    use crate::values::{
        animated::{Animate, Procedure},
        distance::{ComputeSquaredDistance, SquaredDistance},
    };
    use std::iter::FromIterator;

    #[allow(missing_docs)]
    pub fn animate<T, C>(left: &[T], right: &[T], procedure: Procedure) -> Result<C, ()>
    where
        T: Animate,
        C: FromIterator<T>,
    {
        use num_integer::lcm;
        // If the length of either list is zero, the least common multiple is undefined.
        if left.is_empty() || right.is_empty() {
            return Err(());
        }
        let len = lcm(left.len(), right.len());
        left.iter()
            .cycle()
            .zip(right.iter().cycle())
            .take(len)
            .map(|(left, right)| left.animate(right, procedure))
            .collect()
    }

    #[allow(missing_docs)]
    pub fn squared_distance<T>(left: &[T], right: &[T]) -> Result<SquaredDistance, ()>
    where
        T: ComputeSquaredDistance,
    {
        use num_integer::lcm;
        if left.is_empty() || right.is_empty() {
            return Err(());
        }
        let len = lcm(left.len(), right.len());
        left.iter()
            .cycle()
            .zip(right.iter().cycle())
            .take(len)
            .map(|(left, right)| left.compute_squared_distance(right))
            .sum()
    }
}